(Published in the Proceedings of the IASTED “Computers and Advanced Technology in Education” [CATE] 2000 International Conference, May 24-27, 2000)

THE BEST OF BOTH WORLDS: WWW ENHANCED IN-CLASS INSTRUCTION

GREGOR M. NOVAKDept of Physics

Indiana University Purdue University Indianapolisgnovak@iupui.edu

EVELYN T. PATTERSONDept of Physics

United States Air Force AcademyEvelyn.Patterson@usafa.af.mil

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INTRODUCTIONThis paper describes a pedagogical

strategy that combines the best features of traditional in-class instruction with the exciting new communication channels opened by the World Wide Web technologies. Over the past four years we have developed a teaching strategy dubbed “Just-in-Time Teaching” which makes use of the feedback loop between in-class and out-of-class teaching and learning. While this is still a work in progress, we can point to dramatic improvements in retention rates and to significant cognitive gains as well. Encouraged by the participants at national workshops (sponsored by, among others, The National Science Foundation, Project Kaleidoscope and the American Association of Physics Teachers) we have produced a book on the subject [1]. Many people are contributing to this effort. In addition to our close collaborators Prof. Andrew Gavrin at IUPUI and Wolfgang Christian at Davidson College, there are now over thirty JiTT adopters across the US, in disciplines ranging from physics to philosophy to business management.

WHAT IS JUST-IN-TIME TEACHING?

The Just-in-Time Teaching, JiTT, strategy is aimed at many of the challenges confronting instructors and students in today’s classrooms. Student populations are diversifying. In addition to the traditional nineteen-year-old recent high school graduates we now have a kaleidoscope of “non-traditional” students: older students, working part time students, commuting students, and, at the service academies, military cadets. At a minimum these students face time management challenges. They come to our courses with a broad spectrum of educational backgrounds, interests, perspectives, and capabilities that compel individualized, tailored instruction. They also need motivation and encouragement to persevere in what for many is a bewildering, unfamiliar task. Consistent, friendly support often makes the difference between a successful course experience and a fruitless effort, and often it even means the difference between graduating and dropping out [2].

Education research has made us more aware of learning style differences and of the importance of passing some control of the learning process over to the students. Active learner environments yield better results but they

are harder to manage than lecture oriented approaches [3].

To confront these challenges, the Just-in-Time Teaching strategy pursues three major goals:

1. To maximize the efficacy of the classroom session, where human instructors are present.2. To structure the out-of-class time for maximum learning benefit.3. To create and sustain team spirit. Students and instructors work as a team toward the same objective, to help all students pass the course with the maximum amount of retainable knowledge.

Although Just-in-Time Teaching makes heavy use of the web it is not to be confused with either distance learning (DL) or with computer aided instruction (CAI.) Virtually all JiTT instruction occurs in a classroom with human instructors. The web materials, added as a pedagogical resource, act primarily as a communication tool and secondarily as content provider and organizer.

JiTT web pages fall into three major categories:

1. Student assignments in preparation for the classroom activity. WarmUps and Puzzles, discussed in this paper, fall into this category.2. Enrichment pages. We title these pages “What is Physics Good For?” – “GoodFors” for short. These are short essays on practical, everyday applications of the physics at hand, peppered with URL links to interesting material on the web. These essays have proven themselves to be an important motivating factor in introductory physics service courses, where students often doubt the current relevance of classical physics, developed hundreds of years ago.3 Stand alone instructional material, such as simulation programs and spreadsheet exercises.

In this paper we focus on WarmUps and Puzzles.

WHAT ARE JITT WARMUPS AND PUZZLES?

WarmUps and Puzzles are short, web-based assignments, prompting the student to think about a physics related topic and answer a few simple questions prior to class. It can be seen from examples below that some of these questions, when fully discussed, often have

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complex answers. We expect the students to develop the answer as far as they can on their own. We finish the job in the classroom. These assignments are due just a few hours before class time. The responses are collected electronically and scanned by the instructor in preparation for class. They become the framework for the classroom activities that follow. In a typical application, sample responses are duplicated on transparencies and taken to class. In an interactive session, built around these responses, the lesson content is developed.

Students complete the WarmUp assignments before they receive any formal instruction on a particular topic. They earn credit for answering a question, substantiated by prior knowledge and whatever they managed to glean from the textbook. The answers do not have to be complete, or even correct.

Puzzle exercises are assigned to students after they have received formal instruction on a particular topic. They serve as the framework for a wrap-up session on a particular topic.

The WarmUps, and to some extent the Puzzles, are designed to deal with a variety of specific issues. In physics, these can be roughly categorized as follows.

Developing Concepts and Vocabulary Modeling -- Connecting Concepts and

Equations Visualization in General and Graphing

in Particular Estimation, Getting a Feel for

Magnitudes Relating Physics Statements to

“Common Sense” Understanding Equations – the Scope of

Applicability

In preparing WarmUp assignments for an upcoming class meeting we first create a conceptual outline of the lesson content. This task is similar to the preparation of a traditional passive lecture. As we work on the outline we pay attention to the pedagogical issues that we need to focus on when in front of the class. Are we introducing new concepts and/or new notation? Are we building on a previous lesson, and if so, what bears repeating? What are the important points we wish the students to remember from the session? What are the common difficulties typical students will face when exposed to this material? (Previous classroom experience and education research can be immensely helpful here.) Once this outline has been created we create broadly based questions that will force students to grapple with as many of the issues as possible. We are hoping to receive, in the student responses, the framework on which we build the in-class experience. When students leave a JiTT classroom they will have been exposed to the same content as in passive lecture with two important added benefits. First, having completed the web assignment just before classtime, they were ready to actively engage in the classroom activities. Secondly, they will leave with a feeling of ownership since the interactive lecture was based on their own wording and understanding of the relevant issues. To close the feedback loop, the give and take in the classroom suggests future WarmUp questions that will reflect the mood and the level of expertise in the class at hand. Thus, from the instructor’s point of view, the lesson content remains pretty much the same from semester to semester. From the students’ perspective, however, the lessons are fresh and interesting, with a lot of input from the class.

EXAMPLES OF WARMUPS AND PUZZLES.

JiTT web pages can be very simple and yet very effective. The usefulness of the web as a communication tool is in that it is ubiquitous and ever present. It effectively removes the time and space barriers between the classroom and the outside world. However, the web is also a vehicle for delivery of digital image and sound information. Animation can greatly enrich any web page, and animated pages can deliver information that cannot be delivered any other way. We shall call a web page static if it contains text and images, but no animated media

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resources such as movie clips, animations or simulations. Web pages with animated interactive media resources we shall call dynamic.

Below we give some examples of static JiTT and some examples of Java based dynamic JiTT. For the dynamic pages we use Physlets™, java applets developed for physics and science instruction by Prof. Wolfgang Christian of Davidson College [4]. Physlet based simulations can be combined with digital video into a state-of-the art tool for on-line instruction.

A. STATIC PAGE WARMUPSExample 1 (concepts and vocabulary):

During aerobic exercising, people often suffer injuries to knees and other joints due to HIGH ACCELERATIONS. When do these high accelerations occur?

When we introduce the concept of acceleration for the first time, the student already “knows” what we mean by the word accelerate. However in the restricted sense of physics terminology acceleration is defined as the rate of change of the speed or the direction of motion or both. Thus accelerations occur when we speed up (the common notion), but also when we slow down or change direction. Dealing with rates is notoriously difficult. It has to be explicitly, and frequently, pointed out to beginning students that very high accelerations can occur at very low speeds if the rate of change is high, i.e. if the time interval during which the change occurred is very short.

A typical set of student responses will articulate examples of all these issues. Two examples are quoted below.

1. These injuries occur when a runner increases his/her speed and is running faster than 'normal.' People need to slowly build up to a quicker speed instead of diving right into it.

2. Injuries to the knee occur when the foot makes contact with the floor.The acceleration swiftly goes to zero and then back up again in the opposite direction that it was just going. This causes great stress on the knee and is when most of the injuries occur.

Armed with a dozen or so representative responses an instructor can help students come to grips with the notion of acceleration, discussed in the wording of the students themselves.

WarmUp Example 2 (Visualization-

Connecting Concepts and Equations) (thanks to Dr. Andrew Gavrin, IUPUI)

The figure above shows two camera shots of a setup including a business card, a converging lens, a mirror, and the camera. The top and bottom picture differ only in how the camera lens was focused. All of the objects in the setup remained in place. Study carefully, in both pictures, the parts labeled A, B, C and D. Notice for instance that Part D is in sharp focus in the top image but blurred in the bottom image. The reverse is true for part B. Both images were created by light signals propagating from the business card to the camera. For example, in part A light traveled directly from the business card to the camera (we see the back of the business card.)

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Describe the paths that light took from the business card to the camera to create parts B, C and D of the image.

This question is presented to the students after they have studied the properties of lenses and mirrors. They are now asked to integrate that knowledge and construct an explanation of why they see what they see in the above picture. This will prepare them for the lesson on optical systems.

B. DYNAMIC PHYSLET-BASED WARMUPS

If a picture is worth a thousand words, what is an animated picture worth? Java applet technology makes it possible to enhance web pages with interactive animated images and diagrams. Prof. Wolfgang Christian of Davidson College has developed a set of scriptable applets called Physlets™. These applets contain drawing engines for various objects that can illustrate the laws of physics. These applets can be embedded into a web page, with the specific properties of the displayed objects controlled by JavaScript

code on the page. Thus, the user of this technology can create impressive, interactive animation with a relatively modest amount programming expertise, i.e. basic JavaScripting.Physlet-based interactive animations can greatly enhance the usefulness of a WarmUp.

As an example consider the following WarmUp, intended to precede the second period devoted to projectile motion. Students have already worked with the equations of motion.

From the WarmUp web page on the left, the student interacts with the simulation in the Physlet window on the right.

Question 1.Change thex-component of vo to 4 m/s.Click the "try it" button and observe the simulation and the graphs. In a few sentences explain the changes you observe in the graphs.Question 2.Change the y-component of vo to 8 m/s.Click the "try it" button and observe the simulation and the graphs. In a few sentences explain the changes you observe in the graphs.

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Question 3.Write an expression for y as a function of x.

This WarmUp exercise gives a student an opportunity to reflect on the kinematics learned thus far. In particular, the student is forced to think about graphs and their interpretations. Typical students in our experience have a difficult time distinguishing between trajectories and time graphs. Observing the two graphs they are forced to explain why only the y vs. x graph changes in Question 1. The notions they develop are further reinforced in the second question where both graphs change.

We believe it is essential that a thorough classroom discussion follow this exercise while the notions that the students developed as they worked through the WarmUp are still fresh in their minds. The misinterpretations culled out of the student submissions can be addressed through effective demonstrations. Real life demonstrations and activities are needed to support the simulations. Students often accept the simulations, but they don’t believe that they faithfully represent reality.

This type of WarmUp can be extended to a more elaborate self-study review tutorial. More detailed short questions can deal with the relationships between the initial launch speed vo, the launch angle, and the velocity components.

Entire WarmUps can be based on a single Physlet animation or a series of animations, as illustrated above. Often, though, a topic or concept can be particularly well addressed via a WarmUp composed of multiple kinds of questions that represent a variety of approaches: explain/describe, calculate, visualize and interpret, etc. In this case, it is entirely possible

that only one or two of the questions comprising the WarmUp will be Physlet-based.

Because a Physlet-based question inherently involves visualizing or watching something, it probes the students’ understanding in ways not previously possible with a static question.

Consider the following example about rocket propulsion:

The question:An aerodynamics major friend of yours has

designed a rocket and has asked you to take a look at the design. Your friend has programmed the relevant parameters into a Physlet page so that you can better take a look. The Physlet shows the rocket launching from the surface of the Earth.

(a) What do you notice that is strange about this design? (What seems wrong with it?) (b) Use the information provided on the Physlet page (hint: including the elapsed time t) to estimate what the fuel burn rate (dm/dt) of the rocket must be.

The pedagogy behind this WarmUp: As can be seen from the y versus t graph in

the screenshot below, the rocket burns fuel for about 10 seconds before it begins to lift off of the launch pad. (This is also evident in the left Physlet panel; the rocket begins to move upward at about t = 10 seconds.) The student is provided with values for the empty rocket mass (10,000 kg), the initial mass of the fuel (56,000 kg), the total mass of the rocket initially (66,000 kg which is the sum of the previous two masses), the value for the exhaust speed of the rocket (2500 m/s), and the value for g, the acceleration due to gravity (9.8 m/s2). To answer the question,

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the student must realize that the rocket thrust is insufficient to allow the rocket to accelerate upward until some of the initial mass of the rocket is lost due to burning off of ‘extra’ fuel. To estimate the dm/dt fuel flow rate, the student must set the thrust (which is equal to the product of the exhaust speed and the fuel flow rate: T = vex*(dm/dt)) equal to the force of gravity on the rocket at the time it actually begins to accelerate upward, and then solve for the unknown dm/dt.

Sample Student Responses:

Category 1:Students who either focus on superficial features or see nothing ‘wrong’ and who assume that, because the simulation happens to run for 40 seconds, all of the fuel (56000 kg) is expended during that 40 second elapsed time period:

“I don't see anything that is wrong. dm/dt is 1400 kg/s”

“it's only got one booster/fuel tank rolled into the same structure. Also, they usually don't launch from the ground, but up 100 ft or so, so that the thrust can spread out and build. dm/dt=1400 kg/s 56000kg/40s (to burn the fuel)”

Category 2.Students who understand that the rocket doesn’t have enough thrust and/or has too much fuel initially to take off, but who make faulty or unclear starting assumptions to estimate dm/dt:

“The rocket takes entirely too long to get off the ground. After 40 secs the rocket has only reached 200 meters in the vertical direction (I can run this distance 12-15 seconds faster and I'm a distance runner). Since the rocket mass probably isn't the problem here because of the fuel requirements, my aero major friend probably hasn't designed a powerful enough engine for this rocket, or has miscalculated his exhaust velocity. A good thrust to weight ratio would fix this problem. The mass lost rate is approximately equal to thrust/-u= -1.48E4 kg/s assuming a thrust of 37E6 N. To get the exact thrust, I'd have to fit a function to the rocket's displacement versus time graph and take the second derivative of the graph to find out its acceleration, then multiply that value by its instantaneous mass to find the thrust. This would involve Newton's 2nd law.”

“It seems that the rocket is very slow in taking off. It may not have enough thrust. 1000kg/40s = 25kg/s = dm/dt”

“It looks like it has to burn a lot of fuel before it is light enough to leave the ground, because the rocket does not leave the ground for 9 seconds. dm/dt must be close to 22kgm/s”

“The rocket doesn't actually lift off until just before 9 seconds. Take the equation v=-gt+u ln(m_0/m). Maybe u is not sufficient to make v positive, so the rocket will stay on the ground until enough fuel is burnt off...it should be designed so that it lifts of as soon as it reaches a full burn rate (paraphrasing what the book says on pages 92&93). Assume the thrust is about 1,000,000 N, then dm/dt=thrust/-u =-400 kg/s”

Category 3. Students completely grasp the question and can answer it correctly:

“Whoever designed the rocket didn't give it enough thrust: that is, it weighs too much initially to leave the ground. As the fuel burns off, it becomes light enough to fly but not until then. so, you just manipulate the equation from the book to solve for m ,which turns out to be 63,712 so, 66000-63712/9 sec = 254.2 kg/s”

“It seems odd that the rocket sits on the pad for nearly 10 seconds (probably turning the launch pad into slag) while the motor burns off fuel until the upward force generated by the thrust is finally greater than the weight of the rocket. Why waste gas when one could simply load the rocket with less fuel in the first place? What with the high pump prices today. Referring to eq 2.132, I would estimate dm/dt to be approximately 216 kg/s. (This is eerily like problem 2-54)”

A PUZZLE EXAMPLE.Puzzle assignments are more complex than

WarmUps but are given in the same spirit. Students are expected to analyze a situation, apply the relevant physics, and answer specific questions. The in-class activity, based on the student responses, is a summary review of the concepts learned.

You probably know by now, from reading the book and from working the projectile motion problems, that the

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maximum range for a projectile is achieved when the projectile is fired at 45 degrees. This is true if the launch starts and ends at the same altitude. What about if you fire at a target at a lower elevation? Is the optimal angle still 45 degrees? Is it more? Less?Please answer this in words, not equations, briefly explaining how you obtained your answer.

This question allows the student to revisit the concepts and equations of two-dimensional kinematics. It focuses in particular on the relation between the motion in the horizontal direction and the motion in vertical direction. These notions would have been amply discussed in the preceding WarmUps (e.g. the first Physlet-based WarmUp above.) This is the example that ties it all together.

CONCLUSION

In this paper we have examined two types of web assignments from the pedagogical arsenal of the Just-in-Time Teaching strategy, WarmUps and Puzzles. Both types of assignments are used to prime the students for the classroom activity that follows. The assignments ask the students to think deeply about the topic to be studied. Thus a need to know is created which becomes a strong motivating factor for taking the subsequent classroom activity seriously and approaching it with interest. In many instances, Physlet-based simulations can make a substantial contribution to the value of the assignment. In some cases the simulation is the central, essential component. Other web resources employed in the JiTT-based curriculum include enrichment pages with web links, preparatory assignments that prepare students for the hand-on lab, and various communication pages that put students in touch with one another and with the instructors. For more detailed information please examine our book[1] or visit our web sites at http://webphysics.iupui.edu/jitt.html or http://webphysics.iupui.edu/introphysics.

REFERENCES[1]Novak, Gregor M., Patterson, Evelyn T.,

Gavrin, Andrew D., and Christian, Wolfgang. (1999) Just-in-Time Teaching: Blending Active Learning with Web Technology, Prentice Hall, Upper Saddle River, NJ.

[2]Cope, R. & Hannah, W. (1975). Revolving College Door: The Causes and Consequences of Dropping Out, and Transferring, Wiley, New York.

[3]Hake, Richard R. (1998) “Interactive-engagement vs. traditional methods: A six-thousand-student survey of mechanics test data for introductory physics courses,” Am. J. Phys. 66 64-74.

[4]Christian, Wolfgang (1998) and Titus, Aaron, “Developing Web-Based Curricula Using Java Applets,” Computers in Physics 12, 227-232.http://webphysics.davidson.edu/applets

BIBLIOGRAPHYForinash, Kyle. (1999) “Book Review of Just-in-

Time Teaching,” American Journal of Physics, 67 (10), pp. 937-938.

Jonassen, David H. and Grabowski, Barbara L. Handbook of Individual Differences, Learning, and Instruction, New Jersey: Lawrence Erlbaum Associates, 1993.

Langer, Ellen J. The Power of Mindful Learning, Addison-Wesley, 1997.

Laws, Priscilla (1997), “Millikan Lecture 1996: Promoting active learning based on physics education research in introductory physics courses,” Am. J. Phys. 65, 13-21.

McKeachie, W. J., Pintrich, P. R., Yi-Guang, L., and Smith, D. A. F. (1986) “Teaching and Learning in the College Classroom: A Review of the Research Literature.” Ann Arbor: Regents of the University of Michigan.

Sutherland, Tracey E. and Charles C. Bonwell, editors. Using active learning in college classes: a range of options for faculty, San Francisco: Jossey-Bass, 1996.

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